There's two ways that I'm aware of to launch a Chrome app without using the "new tab tab":

1) Use a bookmark. Chrome apps are just bookmarks, after all. If you want to be really clever about it you could even use a (personal, non-social) bookmarking web app like http://bookmarked.us/

2) Install an app that lets you launch other apps. I'm thinking of this one: https://chrome.google.com/webstore/detail/app-launcher/odmpa... (App Launcher)